Contact breaker assemblies



March 3, 1970 Filed May 13, 1968 W. L. FRY

CONTACT BREAKER ASSEMBLIES 4 Sheets-Sheet 1 ATTORN'EYS CONTACT BREAKERASSEMBLIES Filed May 13, 1968 4 Sheets-Sheet 2 INVE NTOR Mai-93% March3, 1970 w, FRY 3,499,128

CONTACT BREAKER ASSEMBLIES Filed May 13, 1968 4 Sheets-Sheet 5 INVE NTORWi /y March 3, 1970 w. L. FRY

CONTACT BREAKER ASSEMBLIES 4 Sheets-Sheet 4 Filed May 13, 1968 INVENTORN 06% United States Patent 3,499,128 CONTACT BREAKER ASSEMBLIES WilliamLawrence Fry, Birmingham, England, assignor to Joseph Lucas (Industries)Limited, Birmingham, England Filed May 13, 1968, Ser. No. 728,399 Claimspriority, application Great Britain, June 12, 1967, 26,9'75/ 67 Int. Cl.H01h 19/00 US. Cl. 200-19 1 Claim ABSTRACT OF THE DISCLOSURE A contactbreaker assembly for use in an ignition dis tributor is in the form of aself contained unit and includes a contact plate adapted to be mountedfor pivotal movement within the distributor. A fixed contact issupported on a tag upstanding from the contact plate, and a sleeve issecured to the contact plate and pivotally supports an insulating heelmember. The heel member carries the movable contact of the contactbreaker assembly, the movable contact being engageable with the fixedcontact. One end of a leaf spring is secured to the insulating heelmember, and the other end of the leaf spring is anchored to the contactplate the spring urging the heel member to pivot in a direction to bringthe movable contact into engagement with the fixed contact.

This invention relates to contact breaker assemblies for use in ignitiondistributors of the kind comprising a casing, a cam shaft journalled forrotation in the casing, a timing plate angularly movable with respect tothe shaft to adjust the ignition timing of the distributor in use, apivot post upstanding from the timing plate, a contact breaker assemblycarried by said timing plate, the contact breaker assembly including acontact plate which is pivotally engaged with said pivot post and whichcarries a fixed contact, a heel member carrying a movable contact whichis movable into and out of engagement with the fixed contact in responseto rotation of the cam shaft and a leaf spring having one end thereofengaged with the cam follower and its other end anchored to the contactplate, the spring urging the movable contact into engagement with thefixed contact, the arrangement being such that pivotal movement of thecontact plate with respect to the timing plate adjusts the gap betweenthe contacts.

In conventional contact breaker assemblies for use in distributors ofthe kind specified the heel member is pivotally engaged with the pivotpost carried by the timing plate and when it is desired to fit a newcontact breaker assembly it is necessary to disconnect the electricalconnections to the movable contact, release a locking screw whichsecures the contact plate to the timing plate, disengage the contactplate and the heel member from the pivot post, then engage the newcontact plate and the new heel member with the pivot post, replace thelocking screw and finally re-connect the electrical connections to themovable contact.

This procedure is cumbersome since it is diflicult to manoeuvre thecontact plate and the heel member into alignment with each other andwith the pivot post against the action of the leaf spring, within theconfines of distributor casing. It is an object of the present inventionto provide a contact breaker assembly for use in a distributor of thekind specified, which is simple to replace by comparison withconventional contact breakers.

According to the invention a contact breaker assembly for use in anignition distributor of the kind specified, comprises a self-containedunit including a contact plate having a hole therein, a fixed contactsupported on the contact plate, a sleeve secured to said contact plateand extending at right angles thereto coaxial with said hole, aninsulating heel member pivotally supported on said sleeve, means formaintaining the heel member in position on the sleeve said means beingsuch that the heel member can be engaged as a snap fit on said sleeve,during construction of the assembly, a movable contact supported on heelmember, a leaf spring having one of its ends secured to said heelmember, and an insulating member carried by the contact plate and towhich the other end of the leaf spring is anchored so that the springurges the movable contact into engagement with the fixed contact, thearrangement being such that when the contact breaker assembly is mountedin a distributor of the kind specified said pivot post extends into saidhole in the contact plate to render the assembly pivotable with respectto the timing plate.

One example of the invention is illustrated in the accompanying drawingswherein:

FIGURE 1 is a fragmentary plan view of a contact breaker assembly withthe spring thereof disengaged from the contact plate,

FIGURE 2 is a sectional view on the line 2-2 in FIG- URE 1 showing theassembly supported on the timing plate of a distributor,

FIGURE 3 is a plan view of the contact plate shown in FIGURE 1,

FIGURE 4 is a view similar to FIGURE 1 with the contact plate omitted,

FIGURE 5 is a sectional view showing the spring anchorage, and

FIGURE 6 is a part sectional plan view of an ignition distributorincorporating the contact breaker assembly shown in FIGURE 1.

Referring to the drawings, the contact breaker assembly includes anarcuate conductive contact plate 11 having a hole 12 adjacent one endthereof. Adjacent the hole 12, the plate is formed with an integralupstanding tag 13 which has secured thereto the fixed contact 14 of theassembly. A hollow sleeve 15 having an outwardly directed flange 16 atits lower end is welded to the plate 11 so as to extend at right anglesthereto, coaxial with the hole 12, and adjacent its upper, free end thesleeve 16 is formed with a pair of diametrically opposite partcircumferential ribs 17.

Pivotally engaged with the sleeve 15 is a moulded synthetic resincontact breaker heel 18 having integral therewith a cam follower portion19. The heel 18 is formed at one end with a pair of arcuate resilientarms 21 which define between them a substantially circular hole 22, thediameter of which is fractionally less than that of the sleeve 15.Moreover, the inner surfaces of the arms 21 are so shaped that thecircumference of the hole 22 includes three flats 23 spaced apart fromone another by approximately In order to engage the heel 18 with thesleeve 15 the sleeve 15 is inserted into the hole 22 defined between thearms 21 and the heel 18 is urged downwardly towards the plate 11. As theheel 18 is urged downwardly the arms 21 flex apart so that the heel 18can ride over the ribs 17 of the sleeve 15. When the heel 18 passes theribs 17 the arms 21 spring towards each other so that the three flats 23engage the sleeve 15. The ribs 17 are so positioned with respect to theplate 11 that they resist upward movement of the heel 18 relative to theplate 11 in use and moreover the arcuate spaces defined between theflats 23 and the sleeve 15 act as lubricant reservoirs in use.

Partially surrounding the heel 18 and secured thereto by a rivet is agenerally U-shaped metal shell 20, the heel 18 including shoulders 20aat the roots of the portion 19 and one of the arms 21 respectivelyagainst which the shell abuts to locate the shell 20 in position on theheel 18. One limb of the shell 20 is extended and carries the movablecontact 24 of the assembly at its free end, and furthermore one end of aleaf spring 25 is secured to the shell 20 by the rivet which secures theshell 20 to the heel 18 and the spring 25 is thereby electricallyconnected to the contact 24. The end of the spring 25 remote from theheel 18 is bent to define a loop 26 and the loop 26 is engaged with agenerally cylindrical insulating member 27 which is a snap fit on a tag28 bent up from the plate 11. Thus the spring 25 is anchored to theplate 11 and urges the heel 18 to pivot about the sleeve 15 in adirection to engage the contact 24 with the contact 14.

-In use the assembly is supported on the timing plate 29 of an ignitiondistributor which in turn is pivotally mounted on a base plate 30asecured to the casing 30 of the distributor. The cam shaft 30b of thedistributor extends through the plate 30a and the plate 29 and the plate29 is rotatable relative to the cam shaft to vary the ignition timing ofthe distributor. In conventional distributors the plate 29 has securedthereto an upstanding post and the assembly is engaged with the plate 29with the post extending upwardly through the hole 12 in the plate 11 andinto the sleeve 15. The plate 11 is formed with an arcuate slot 31struck from the centre of the hole 12 and in use a screw 31a extendsthrough the slot 31 into engagement with plate 29 the screw 31a beingtightened to clamp the plate 11 to the plate 29. The plate 11 ispivotable about the post to move the contacts 14, 24 towards or awayfrom the cam shaft so as to vary the operating gap between the contacts14, 24, the screw being tightened to clamp the plate 11 in positionrelative to the plate 29.

In a modification shown in FIGURE 2 the post secured to the plate 29 isdispensed with and the plate 29 is stamped to form a short upstandingpost 32. When the contact breaker assembly is engaged with the plate 29the post 32 extends into the hole 12 in the plate 11 to render the platepivotable on the plate 29.

The plate 29 is earthed in use and the member 27 is provided with anintegral screw threaded spigot 27a. An annular terminal electricallyconnected through the primary winding of an ignition coil to a DC.source is engaged with the spigot 27a so that it rests on the loop 26 ofthe spring 25 and a nut is engaged with the spigot 27a and screwed downto clamp the terminal firmly in contact with the loop 26. Thus thecontact 24 is connected to the DC. source through the spring 25, theterminal and the primary winding of the ignition coil and the contact 14is earthed through the plate 11. The portion 19 of the heel 18 rides onthe shaft of the distributor so that as the cam shaft rotates themovable contact 24 is moved into and out of engagement with the contact14 so as to make and break the circuit to the primary winding of thecoil. The high tension electrical pulses generated in the secondarywinding of the ignition coil by the make and break of the circuit to theprimary winding are of course directed to the sparking plugs of aninternal combustion engine by the distribution part of the ignitiondistributor.

In a further modification (not shown) the sleeve 15 is formed with acircumferential groove in place of the ribs 17 and the hole 22 is formedwith a circumferential rib which engages as a snap fit in the groovewhen the heel 18 is positioned on the sleeve 15. Moreover the contact 24is domed and the contact 14 is flat and of larger diameter than thecontact 24 thereby providing a greater margin for error in thepositioning of the contact 24 relative to the contact 14 than is presentin conventional contact breaker assemblies.

In use, it is found that there is a tendency for the plate 11 to tiltrelative to the plate 29 when the screw 31a is tightened to clamp theplate 11 to the plate 29. In order to minimise tilting of the plate 11,the plate 11 is provided, adjacent the slot 31 with a downwardlydirected projection 33 which engages the plate 29 asthe plate 11 isclamped to the plate 29. Conveniently, the projection 33 is formed byhalf shearing an area of the plate 11 adjacent the edge thereof.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A contact breaker assembly for use in an ignition distributorcomprising, a self contained unit including a contact plate having anaperture therein, a fixed contact supported on the contact plate, asleeve secured to said contact plate and extending at right anglesthereto coaxial with said aperture, an insulating heel member having apair of curved resilient arms which define between them a hole, saidsleeve extending through said hole so as to mount said heel member forpivotal movement, an outwardly extending surface on said sleeve saidsurface maintaining the heel member in position on the sleeve and beingsuch that the heel member can be engaged with the sleeve as a snap fit,during construction of the assembly, as permitted by flexure of saidcurved resilient arms, a movable contact supported on the heel member, aconductive leaf spring having one of its ends secured to the heelmember, and an insulating member carried by the contact plate, theinsulating member being engaged as a snap fit with a part integral withthe contact plate and the insulating member having the other end of theleaf spring anchored thereto so that the leaf spring urges the movablecontact into engagement with the fixed contact, the arrangement beingsuch that when the contact breaker assembly is mounted in a distributor,a pivot post extends into said aperture in the contact plate to renderthe assembly pivotable with respect to a timing plate of thedistributor.

References Cited UNITED STATES PATENTS 2,696,534 12/ 1954 Mallory 200-302,727,104 12/1955 Filko 200-30 2,769,046 10/1956 Russell 200-312,896,035 7/1959 Harrington et al 200-30 3,003,043 10/1961 Meyer et al200-19 XR ROBERT S. MACON, Primary Examiner I R. SCOTT, AssistantExaminer U.S. Cl; X.R.

